Activities of tyrosine hydroxylase, dopamine beta hydroxylase and choline acetyltransferase were examined in sympathetic ganglia of Fischer-344 rats at different ages. Increased activities of some of these enzymes were noted in the superior cervical ganglia, adrenal glands and hypogastric ganglion of older rats, suggesting enhanced neurotransmitter synthesis with age. Age changes in catecholamine histofluorescence and lipopigment autofluorescence in sympathetic ganglia from the rat and from humans.